JP2715655B2 - Non-contact type moving amount measuring method and device - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a non-contact type moving amount measuring method and an apparatus therefor. The present invention relates to a method for measuring a minute and impact-related moving amount, for example, an injection amount of a diesel injection pump for an automobile. It can be used as a measuring method and apparatus.

[Conventional technology]

2. Description of the Related Art Conventionally, non-contact type movement amount measuring methods are roughly classified into an increment method and an absolute method. Tokuhei 1-
No. 23048 discloses an increment type moving distance measuring apparatus. In this measuring device, a slit plate that moves together with an object to be measured is provided, and light is emitted toward the slit plate. Then, the light that has passed through the slit is detected by a photodetector, and the amount of movement of the slit plate, that is, the amount of movement of the object to be detected is measured by counting the number of light that has passed.

On the other hand, Japanese Patent Publication No. 1-22884 discloses an absolute-type moving distance measuring device. In this measuring device, a coded slit is formed on a slit plate that moves together with an object to be detected, and the slit plate is irradiated with light. Then, by detecting the light passing through the slit with a photodetector, the slit position before and after the movement of the detection target is detected. Since the distance from the reference position to each slit is measured and stored in advance, the amount of movement of the slit plate is detected by measuring the position of the slit through which light passes after the movement of the slit plate.

[Problems to be solved by the invention]

The conventional moving distance measuring method and apparatus described above have the following problems.

In the increment method, the number of slits passing through the photodetector is measured by a counter.If the movement of the detected object is extremely fast, the counter cannot follow the high-speed movement of the slit, and the amount of accurate movement is measured. There is a problem that can not be.

On the other hand, in the case of the absolute type, there is no problem in followability, but measurement during movement is not possible, and the minimum measurement unit of the movement distance depends on each slit interval formed in the slit plate. Therefore, when trying to measure even a minute movement, it is necessary to physically narrow the slit interval, and there is a problem that measurement cannot be performed to a minute range after all.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a method capable of satisfactorily following a high speed movement of an object to be measured and measuring a moving distance to a minute range, and an apparatus for achieving the method.

[Means for solving the problem]

In order to achieve the above object, according to the present invention, a slit plate having a plurality of slits having different shapes is installed so as to move in a predetermined direction in accordance with the movement of an object to be measured, and a measuring light emitted from a light emitting unit is projected. By passing through an optical lens to be parallel light, the parallel measuring light is passed through the slit plate, and the measuring light passing through the slit is collected in a direction parallel to the moving direction of the measurement target. The light is passed through a condensing lens composed of a convex lens, and is disposed at a position such that the distance between the focal point of the condensing lens and the light receiving surface is larger than the distance between the condensing lens and its focal point. The light receiving means having a light receiving area larger than the width in the moving direction of the slit is made to receive light, the light receiving means detects the presence or absence of light reception within the light receiving area, and based on the detection result of this light receiving presence or absence. Measuring a distance from a boundary of light reception in the light reception range to a specific position in the light reception range serving as a reference position, based on the detection result of the light reception, and measuring the distance among the plurality of slits. The measurement object corresponding to the distance from the boundary line of the presence or absence of light reception in the light receiving range to a specific position in the light receiving range, which is calculated in advance, for each slit, and specifies a slit through which light passes. The method of detecting the movement amount of the measurement target based on the relationship of the movement amount of the measurement target is adopted.

In order to achieve this method, in the apparatus of the present invention, a slit plate having a plurality of slits having different shapes that moves in a predetermined direction with the movement of the measurement target, and a light emitting unit that emits measurement light toward the slit plate A light projecting lens provided in an optical path between the light emitting means and the slit plate to make the measurement light emitted from the light emitting means parallel light; and a light receiving range larger than a width of the slit in the moving direction. And a light receiving unit that receives the measurement light passing through the slit, and emits a detection signal indicating whether or not the measurement light is received within the light receiving range, provided in an optical path between the light receiving unit and the slit plate, A condensing lens formed of a convex lens for condensing the measurement light passing through the slit in a direction parallel to a moving direction of the measurement target, and receiving the detection signal from the light receiving unit, A distance measuring unit that measures a distance from a boundary line of the light receiving range within the light receiving range to a specific position in the light receiving range, and a position measuring unit that emits the measurement signal; A slit detecting unit that specifies a slit through which the measurement light passes among the slits and emits a slit specifying signal, and, for each slit, a relationship between a movement amount of the measurement target corresponding to a distance measured by the position detecting unit. In advance, and has a movement amount detection means for detecting the movement amount of the measurement target from the measurement signal from the position measurement means and the slit identification signal from the slit detection means, the focusing lens and its focus The light receiving means is arranged with respect to the condenser lens at a position where the distance between the focal point of the condenser lens and the light receiving surface of the light receiving means is larger than the distance of Non-contact type moving amount measuring device.

[Action]

After the measurement object moves, the measurement light from the light emitting means passes through the slit. The measurement light having passed through the slit passes through the condenser lens and is received by the light receiving means. The light receiving means is arranged so that the distance between the focal point of the condenser lens and the light receiving means is larger than the distance between the condenser lens and its focal point. The light is received by the light receiving means in a state of being enlarged in the moving direction of the light. The slit through which the measurement light passes is specified based on whether or not the measurement light is received within the light reception range, and how far from the end of the light reception range the measurement light is received is measured. Since the light receiving position for each slit and the moving amount of the measurement object are stored in advance, if the slit through which the measurement light passes is specified and the light reception position of the measurement light is detected, the measurement object is detected. The distance traveled is automatically measured.

〔Example〕

An example in which the measuring method and device of the present invention are used for measuring the injection amount of a diesel injection pump will be described.

FIG. 3 is a cross-sectional view showing an injection amount measuring device of the diesel injection pump, and a schematic configuration of the device will be described based on this drawing. A piston 10 to be measured is slidably disposed in a cylindrical guide 12 while maintaining liquid tightness. The injection liquid from the diesel injection pump is introduced into the cylindrical space 11 formed by the guide 12 and the piston 10, and the piston 10 rises upward in the figure according to the amount.

A slit plate 22 having a plurality of slits 23 is fixed to an upper end of the piston 10. The slit plate 22 reciprocates in the direction indicated by the arrow X in FIG. A pair of guide rollers 24 for preventing the slit plate 22 from rotating and for guiding the reciprocating movement thereof are arranged on the tip side of the slit plate 22 so as to sandwich the slit plate 22.

On one side of the slit plate 22, a lamp 16 as a light emitting means is arranged. The lamp 16 is connected to a power supply 15 and emits measurement light (hereinafter abbreviated as light). A light projecting lens 18 is provided between the lamp 16 and the slit plate 22 so as to convert light diverged from the lamp 16 into parallel light. In addition, on the other side of the slit plate 22, a condensing lens 20 composed of a double-sided convex lens that expands the light passing through the slit 23 from the lamp 16 in the moving direction of the piston 10 is further arranged.
A line sensor 26, which is a light receiving means for receiving the light, is provided. The line sensor 26 is disposed at a position where the distance between the focal point of the condenser lens 20 and the light receiving surface of the line sensor 26 is larger than the distance between the condenser lens 20 and the focal point thereof. Is done. The line sensor 26 is composed of a plurality of light receiving elements, for example, a CCD or the like. Then, the received light signal is transmitted to an amplifier 32 described later.

The lamp 16, the light projecting lens 18, the condenser lens 20, the slit plate 22, and the line sensor 26 are all housed in a housing 14, and have a structure in which light from the outside does not enter the housing 14. Has become.

FIG. 1 is a diagram showing a circuit for processing a light receiving signal from the line sensor 26.

A drive circuit 28 is connected to the line sensor 26. The drive circuit 28 transmits a start signal for instructing the start of the operation of the line sensor 26, an end signal for instructing the end, and a clock pulse. The output side of the line sensor 26 is connected to an amplifier 32 for amplifying the output of the line sensor. The output of the amplifier 32 is connected to a comparator 34,
Is compared with a reference value and converted into a digital signal of “1” or “0”.

The comparator 34 includes a first flip-flop circuit 36 and an inverter.
It is connected to a second flip-flop circuit 42 via 40. The J input terminal of the first flip-flop circuit 36 is always set to "1", and the K input terminal is always "0".
Set to state. The digital signal from comparator 34 is
Input to the CK input terminal. Q output terminal is first AND circuit
The output terminal is connected to the second AND circuit 44. An end signal from the drive circuit 28 is input to the CLR terminal.

The inverter 40 outputs the digital signal “0” from the comparator 34.
Invert the "1" state. The inverted signal is input to the second flip-flop circuit 42. The J input terminal of the second flip-flop circuit 42 is always set to "1" state, and the K input terminal is always set to "0" state.
The Q output terminal is connected to the second AND circuit 44. CLR
An end signal from the drive circuit 28 is input to the terminal.

The clock pulse from the drive circuit 28 is input to the first AND circuit 38, and the first flip-flop circuit
An AND signal with a signal from the Q output terminal 38 is input to the first counter 48.

The output signal of the second AND circuit 44 is input to a third AND circuit 46, and a clock pulse from the drive circuit 28 is also input to the third AND circuit 46. Then, the AND signal of both signals is transmitted to the second counter 50.

The first counter 48 and the second counter 50 start measuring the number of pulses of the input signal in response to the start signal from the drive circuit 28, and end the measurement in response to the end signal. First counter 48
The measurement result y and the measurement result z of the second counter 50 are input to the converter 52, and an address (y, z) is generated in the converter 52. This address (y, z) is
Switching of the data storage means 58 during calibration of the measuring instrument.
At the time of movement amount measurement, and is sent to the position information generating means 60.

When calibrating the measuring device, the reference length measuring device
30 is connected. The reference length measuring device 30 is composed of an increment type optical sensor, and detects a moving amount of the slit plate 22 from a reference position. This detection signal is sent to the converter 62,
It is converted to the actual movement amount x. This movement amount x is sent to the data storage means 58, and is stored in the data storage means 58 together with the measurement results y and z measured at the same time as reference data of (x, y, z). When the calibration of the measuring device is completed in this way, the reference length measuring device 30 is removed, and the slit plate 22 is connected to the piston 10 as described with reference to FIG. A switch 54 is arranged between the converter 62 and the data storage means 58, and connects the converter 62 and the data storage means 58 during calibration, and separates them during measurement. Switches 56 and 54 above
Are linked to each other.

The position information generating means 60 is sent from the converter 52 (y, z)
Based on the information, the corresponding movement amount x is searched for from the data stored in the data storage means 58 and displayed by the display means 62 such as a cathode ray tube.

Next, the operation of this device and the measuring method will be described with reference to the waveform diagram of FIG.

First, calibration for storing (x, y, z) reference data in the data storage means 58 is performed. This calibration method will be described later. After calibration is completed, slit plate 22 is
Connect to 10. Then, fuel or another fluid is injected into the cylindrical space 11 in the guide 12 from a diesel injection pump (not shown). This fluid ejection causes the piston 10 to move upward in FIG. 4, and the slit plate 22 also moves.

The lamp 16 emits light upon receiving power supply from the power supply 15, and the light becomes parallel light by the light projecting lens and passes through the slit 23. The light that has passed through the condenser lens 20 is collected in a direction parallel to the moving direction of the piston 10.
With respect to the condenser lens 20, the line sensor 26 is located at a position where the distance between the focal point of the condenser lens 20 and the light receiving surface of the line sensor 26 is larger than the distance between the condenser lens 20 and its focal point.
, The light passing through the condenser lens 20 is received by the line sensor 26 in a state where the light is expanded in the moving direction of the piston 10.

The line sensor 26 receives the start signal S from the drive circuit 28 and emits a signal corresponding to the intensity of light detected by the light receiving elements arranged on the light receiving surface (indicated by a waveform A in FIG. 2). After being amplified by the amplifier 32, it is compared with the threshold value L by the comparator 34 and converted into a digital signal of "0" or "1" (waveform B). The converted signal is input to the first flip-flop circuit 36. The J input terminal of the first flip-flop circuit 36 is always set to the "1" state, and the K input terminal is always set to the "0" state.
Therefore, while the signal from the comparator 34 is in the “0” state, the signal in the “1” state is output from the Q output terminal, and when the signal in the “1” state is input from the comparator 34, the Q output terminal Outputs a signal in the “0” state (waveform C).

Since the signal from the Q output terminal of the first flip-flop circuit 36 and the clock pulse from the driving circuit 28 are input to the first AND circuit, while the signal from the Q output terminal is in the "1" state. Clock pulse of the first AND circuit
Output from 38 (waveform F). The number of the clock pulses is measured by the first counter 48. This measured number y corresponds to the distance from the reference position H on the light receiving surface of the line sensor 26 (the end of the light receiving range in this embodiment) to the first edge of the slit 23.

From the output terminal of the first flip-flop circuit 36,
A signal obtained by inverting the output signal from the Q output terminal is output, and the output signal of the comparator 34 changes from the “1” state to the “0” state from the Q output terminal of the second flip-flop circuit 42. A signal in a "1" state is output until time (waveform D).
The second AND circuit 44, which receives the signal from the output terminal of the first flip-flop circuit 36 and the signal from the Q output terminal of the second flip-flop circuit 42, outputs a signal corresponding to the width of the slit 23. (Waveform E). Since the width of each slit 23 is set to be different from each other,
If the width of 23 is known, it is possible to know which slit 23 light is passing through.

Since the output signal of the second AND circuit 44 and the clock pulse from the drive circuit 28 are input to the third AND circuit 46, the third AND circuit 46 outputs a clock pulse corresponding to the width of the slit 23. (Waveform G). The number of the clock pulses is measured by the second counter 50.

The measured number y of the first counter 48 and the measured number z of the second counter 50 are input into the converter 52 to generate an address of (y, z). This address is read by the position information generating means 60, and the slit plate movement amount x corresponding to this value is read from the reference data stored in the data storage means 58. And
The moving amount x is displayed on the display means 62. If the movement amount of the slit plate 22, that is, the movement amount of the piston 10, is measured,
The injection amount of the diesel injection pump can be known.

When one measurement as described above is completed, the end signal K is transmitted from the drive circuit 28, and the first flip-flop circuit 36,
The signal is input to the CLR terminal of the second flip-flop circuit 42. As a result, the outputs of both flip-flop circuits return to the initial state. The end signal K is also transmitted to the first and second counters, and both counters end the measurement of the number of pulses.

Next, a calibration method for storing the reference data in the data storage unit 58 will be described.

First, the reference length measuring device 30 is connected to the lower end of the slit plate 22. Then, the slit plate 22 is moved by a minute distance by means such as a micrometer. Then, the position of the slit plate 22 for each movement is measured by the reference length measuring device 30, and the value is converted by the converter 62 into an actual movement amount x from the reference position. At the same time, the measurement number y and the measurement number z are measured by the above-described measurement method, and the value of the movement amount x corresponding to the measurement numbers y and z is stored in the data storage unit 58. This gives x, y, z
Is generated as a reference. During this calibration, the switch 54 is switched so that the converter 62 and the data storage means 58 are connected, and the switch 56 is switched so that the converter 52 and the data storage means 58 are connected. As described above, the light that has passed through the slit 23 is received by the line sensor 26 while being expanded in the movement direction of the piston 10, so that the movement amount of the piston 10 is arranged on the light receiving surface of the line sensor 26. The amplified light can be amplified to a level that can be detected by the light receiving element, and the resolution of the line sensor 26 can be improved. As a result, measurement can be performed even when the amount of movement of the piston 10 is in a minute range.

In the above embodiment, the lamp 16 is used.
As shown, a strobe light source 161 can be used. In this case, the start signal from the drive circuit 28 is transmitted to the synchronous lighting circuit 162, and in response to this, the strobe is lit with a light emission time of 1.1 microseconds.

By using such a strobe light source 161, displacement during high-speed movement can be measured. For example, synchronizing the strobe light emission with the charge accumulation time of the CCD and setting the strobe light emission time to 1 microsecond has an effect that a movement of 1 MHz can be captured.

With the above-described measurement method and apparatus, the measurement accuracy can be increased to the resolution of the line sensor, and in this embodiment, measurement up to a resolution of 0.6 μm is possible. Further, since the movement amount after the movement of the slit plate is completed is measured, even if the slit plate is moved by impact, the movement amount measurement is not affected at all.

〔The invention's effect〕

As described above, the use of the measuring method and apparatus of the present invention makes it possible to favorably follow the high-speed movement of an object to be measured and to measure the moving distance to a minute range.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a waveform diagram showing output signals of each circuit, FIG. 3 is a sectional view showing an embodiment device, and FIG. 4 shows another embodiment device. It is sectional drawing. 16 ... lamp (source), 22 ... slit plate, 23 ... slit, 26 ... line sensor (receiving means).

Claims (5)

(57) [Claims] 1. A slit plate having a plurality of slits having different shapes is installed so as to move in a predetermined direction along with the movement of an object to be measured, and measurement light emitted from a light emitting means is passed through a light projecting lens. A collimating lens consisting of a convex lens for making the parallel measuring light pass through the slit plate, and collecting the measuring light passing through the slit in a direction parallel to the moving direction of the measuring object. With respect to the condenser lens, the condenser lens is disposed at a position where the distance between the focal point of the condenser lens and the light receiving surface is larger than the distance between the condenser lens and the focal point thereof, and the moving direction of the slit. The light receiving means having a light receiving area larger than the width of the light receiving means detects the presence or absence of light reception within the light receiving area, and based on the detection result of the light receiving area, Measure the distance from the boundary line of the presence or absence of light to a specific position within the light receiving range that is the reference position, and based on the detection result of the presence or absence of light reception, the slit through which the measurement light passes among the plurality of slits Is determined in advance, for each of the slits, based on the relationship between the amount of movement of the measurement object corresponding to the distance from the boundary line of the presence or absence of light reception in the light receiving range to the specific position in the light receiving range within the light receiving range. A non-contact type moving amount measuring method for detecting the moving amount of the object to be measured. 2. A slit plate having a plurality of slits having different shapes and moving in a predetermined direction with movement of an object to be measured, light emitting means for emitting measurement light toward the slit plate, light emitting means and the slit A light projecting lens that is provided in an optical path between the light emitting device and a parallel light beam of the measurement light emitted from the light emitting unit, and has a light receiving range larger than a width of the slit in a moving direction, and has passed through the slit. Light-receiving means for receiving the measurement light and emitting a detection signal indicating whether or not the measurement light is received within the light-receiving range; provided in an optical path between the light-receiving means and the slit plate, the measurement passing through the slit A condensing lens comprising a convex lens for condensing light in a direction parallel to the moving direction of the measurement target; and receiving light from the light receiving means to detect the presence or absence of light within the light receiving range. A distance measuring unit that measures a distance from a boundary line to a specific position in the light receiving range, and emits the measurement signal. Upon receiving the detection signal from the light receiving unit, the measurement light out of the plurality of slits is A slit detecting unit that specifies a slit to pass through and emits a slit specifying signal, and for each of the slits, stores in advance a relationship between a movement amount of the measurement target corresponding to a distance measured by the position detecting unit and the position. Moving amount detecting means for detecting a moving amount of the object to be measured from a measurement signal from a measuring means and a slit specifying signal from the slit detecting means, wherein the light is collected more than the distance between the condensing lens and its focal point. The non-contact type wherein the light receiving means is disposed with respect to the condenser lens at a position where the distance between the focal point of the lens and the light receiving surface of the light receiving means is larger. Type travel distance measuring device. 3. The non-contact type moving amount measuring apparatus according to claim 2, wherein said light emitting means is a strobe for irradiating said measuring light at regular time intervals. 4. The apparatus according to claim 2, wherein said light receiving means has a waveform shaping means for shaping a waveform into a digital signal by comparing an intensity signal of said measuring light received in said light receiving range with a reference value. The non-contact type movement amount measuring device according to the above. 5. The non-contact movement according to claim 2, wherein the specific position of the light receiving means within the light receiving range is an end of the light receiving range. Quantity measuring device.